The crystal structure of a ferredoxin is shown below. This particular one is not from photosystem I (it is found in a nitrogen-fixing bacterium), but it gives you the idea. The protein is simple enough that you can see that it is a dimer; the top half is the same as the bottom half, flipped over. You can also clearly see a 2Fe2S cluster at the edge of each subunit. The location of that FeS cluster near the edge of the protein is probably important in facilitating electron transfer with another protein.
The cristae increase the surface area for packing in many electron transport
systems and ATPase molecules - the mitochondria is specialised for electron transport and uses oxygen to drive the ETS and
uses the resultant proton gradient to make ATP for the whole eukaryotic cell.
That's the main role of the electron transport chain
The host cell can not make ATP by electron transport in aerobic respiration without
mitochondria, but it does carry out glycolysis in the cytosol and then transports the end product, pyruvate, into the
mitochondria where it is used in Kreb's cycle which takes place in the mitochondrial matrix (the 'mitochondrial cytosol').
What role does iron have in photosynthesis?
Light absorbed by chlorophyll drives a transfer of electrons and hydrogen from water to an acceptor called (nicotin-amide adenine dinucleotide phosphate), which temporarily stores the energized electrons.
Exam 3 Photosynthesis, Cell division
Also visible in the ligand-only view is a group of FeS clusters. These clusters play a role in the electron-transport chain of photosystem I, conducting the electron toward the stroma, where they will be used to reduce NADP+ to NADPH. That biological reducing agent, closely related to NADH, will be used to help reduce carbon dioxide.
The above illustration draws from ideas in both Moore, et al
Water (H2O) is split in this process, releasing oxygen (O2) and hydrogen ions (H+). The electrons from the electron transport chain combine with these H+ ions and nicotinamide adenine dinucleotide phosphate ions (NADP+) to form adenosine triphosphate (ATP) and a reduced unit of NADP+, called NADPH (NADP plus an electron, or H). These energy storage forms, ATP and NADPH, are used to convert carbon dioxide (CO2) to build carbohydrates during the second phase of photosynthesis. Plants can then break down these carbohydrates to fuel their existence.
Photosynthesis (The Light Reactions) ..
As molecules of NADP' and ADP bump into the thylakoid membrane, they pick up electrons and phosphate, respectively, and then transfer their high-energy cargo to the Calvin cycle.